I am defeated

Another fix might be spelled INTAKE MANIFOLD GASKETS.

Just a thought, though........do you have either stopnuts or lockwashers on your head to manifold interface nuts?  The forces on the intake manifold as a torque arm are ferocious and can tend to loosen the lower manifold nuts in very short order.

I don't think the Webers are at fault just yet.  They could very well be at fault, but let's see if you can get them happy, first.  BTW, do you happen to have an air/fuel monitor on board or kicking around the shop?

I assume you mean the intake manifold-to-head attachments.  I have not checked these at all, and have a hard time aligning the symptoms (on-again-off-again misbehavior, and such a stunning, tho short lived, improvement after the carb R&R w/ cleaning) on something that gets loose.  How does it spontaneously get tight again, then loose again??  Just sayin' . . .

Nevertheless, I will endeavor to look there and check.

Settings change as things heat up. 

Does the car run well when temps are cooler?

Floats set between 10-11?

Have you checked your exhaust? Everything tight?

Are you sure it's carb-related, not ignition?

Do you have a fuel pressure gauge? Electric fuel pump?

Sometimes a defective coil may cause problems. As the engine warms up, the coil may act up due to broken windings.

Gary

CMC project

4 psi is to high for pump pressure. Get it down to 2.8 - 3.2 3.5 max. 3.0 being ideal. Your mixture screws out 2.5 turns is excessive. Without engine info would be a shot in the dark. Start with the pressure webers are happiest at 3 psi. Do a plug check to determine if problem is at all cylinders or otherwise. If you have a timing light that can be attached to the plug wires try each one to see if the strobe is consistent without interuption prior to removing plugs. This will show you which cylinder/cylinders are not firing consistently.

I'll try to answer/address, in order:

The Spin around the block was engine cool to warming; run today was at full operating temps, warmer toward the end of the day, but still way down to the left on the gauge; will run it tomorrow after full cool down and will see if different.

Floats set to spec.

Exhaust seems tight

Ignition (electronic distributor) is good, so far as I know -- will do some test to find out, as indicated below.

Have pressure gauge, and electric fuel pump. Runs around 3.5-4.0 psi

Don't know how to check the coil aside from replacement.  Could measure resistance, but don't know what it should be . . .

Mixture screws will be tweaked. Not sure what engine info you need: is a T1 2332 w/ Weber 44 IDFs

Will do a plug check and report back

Have electronic timing light, will do tests as indicated.

Fuel pump puts out what it puts out -- don't know how to change pressure aside from replacement.  Maybe buy a regulator??

And how are some of these things intermittent, sometimes on, sometimes off?  For example, Fuel pressure is constant.

Daang, Kelly---bummer.  Nothing as frustrating as somethat just seems impossible when you know it should be fixed after a lot of good work.

Maybe think about a set of Dells?  All I hear about them is good.

Hope you are well.

How old are your plug wires?

Make sure your running copper core spark plugs NOT PLATINUM. It sounds like a coil or ignition issue to me. I have worked on Webers for almost 20 years, there not always the problem. 

95% of all carburation problems are ignition. I've wasted a lot of time chasing down something that wasn't broken, and almost burned my car down in the process.

Just a question along those lines: what kind of plug wires are you using?

Kelly......   Check the inside of your dizzy cap.....   I've seen cracks and carbon tracks cause similar problems on '70s and '80s GM iron....   Also check TOTAL resistance of the plug, plug connector, plug wire, cap, and rotor.....   Each of these is available with built in resistors and if used together can cause all sorts of problems as humidity increases and decreases....  Any one of these items will suffice for radio suppression...   Just a thought...

X2 on the ignition system possibility.  I had some similar issues that eventually turned out to be a failing coil.

The reason I ask about the wires: I had some really nice Taylor 8 mm wires that used "conventional" boots on the plug ends. Because VWs use the size-tiny threaded posts on the lead-end of the spark-plug (with the special bake-lite push-on ends), using conventional wires means threading on the little adapter that comes with new plugs.

I could not make the little adapters stay threaded down tight for any amount of trying. Putting a thread-locker on was not an option because that's how the wire makes contact with the plug. They kept backing out and creating a poor connection, and causing a miss just enough of the time to be a complete mystery. I though it was carburation. It was not.

When I went back to the plebeian 7 mm Bosch plug-wires and threw away the stupid adapters on the plug tips, the problem went away immediately.

It's the little foxes that spoil the garden (Song of Solomon 2:15)

 This crappy gasoline is a big part of our problems  I went 2 heat ranges higher on my plugs and a 65.00 volt coil to get the beetle to behave and it still has a single 31  solex carb    Its the benzene they are adding to the winter fuel.. it make mine cold natured as all get out I even bead blasted my  heat riser ports to make sure they were clear and allowing heat transfer into the intake..   Its sickening ..

I am all about chasing the little foxes now.  I am, as you can likely tell, very discouraged at the moment.  The plug wires are as new as the car: 11K mi, six years?? and seem fine.  Connections good, but I will check them out as much as I can.

As to the coil, should I just go buy a new one?  What diagnosis can be done on the old one??  And if buy a new one, just replace, or upgrade?  To what??

Irony:  There is a local fellow who has contacted me about his desire to buy a Speedster.  He wants to see a JPS up-close, and talk to an owner.  He's coming by today at 3:00.  I told him it was running for sh**, and he is coming by anyway.

Not good enough; you need to know definitively if the components you are checking are in good working order, otherwise you'll keep chasing your tail until one day (by sheer luck) you fix the problem. But that's taking a while...
Do you own a multimeter?

Someone above mentioned the coil; I've heard of coils testing fine but acting up when they get warm (and coils do get warm when bolted to the fan shroud in the engine compartment.

Ditto on the heated coil. Happened to me. Plug wires? Yep. 

Kelly, where is your gas filter? Hopefully not in the engine bay, where John put mine.

Don't trust your VDO oil temp cluster gauge unless you have calibrated it.

My guess is ignition.  Ck rotor, cap, condensor, coil also the ballast resistor could be going.  You need 7 to 8 volts at the hot side of the coil when running.  I had the center post fall out of a rotor and the car

ran like hell

The plug isolators and go bad just setting  and a meter is the only way to correctly check um

The twisting and turning of opinions on this problem is getting exciting!

I'm tuning in bright and early tomorrow hoping this engine performance mystery has been identified...and to find out what diagnostic proceedure(s) pit-points the problem. Because I can't help but think... "There but for the grace of God, go I" 

The bad news: the car runs lousy.

The good news: every ignition component on the car can be replaced for about $200. I realize that it sounds elitist to say "only $200"-- but everybody here has a bit of disposable income, or we wouldn't have purchased the cars in the first place. Try getting anything done to a 911 for $200.

I've had a bad CDI box make my car run bad. I've had a bad center pin in the distributor cap make the car run bad. I've had the aforementioned plug-wire incident make the car run bad. I have not one, but two Mallory Uni-Lite distributors, and 2 spare caps and my car won't run well on any of it. Ignition parts are junk, and ignition is almost always the problem.

In my case, it often feels like carburation is the issue-- but it almost never is. 

Kelly- if I were you, I'd hook up with a nearby speedster buddy (somebody who's car is running well), and start swapping ignition parts out until the car runs well. If you have stock Bosch wires, I'm guessing it's the coil, or something in the cap/rotor. Regardless, you could swap the coil, the cap and rotor, and all the wires in about 15 minutes. You'd know if it was ignition or not.

I keep an 009 and Bosch blue coil in a drawer to eliminate ignition as a possible source of problems. I'm the biggest retro-grouch on the site, and I'm thinking of going to mega-jolt crank-fire this winter to eliminate the ignition mess that we all live with. Danny Pip raves about his-- says it's the best mod he's made to his car.

If this all sounds like too much, just take it to somebody. Life's too short to lose an entire summer of driving to something silly.

I believe it is the Distributor as it heats up, happened to me, very frustrating, A friend stopped by with a VW and within 5 minutes swapped his for mine and poof found the problem. 

Peace

OK, I get the message: check ignition.  I did check the dist cap (looks fine, clean as a whistle) and the Bakelite plug connections -- they were a little dirty, so I cleaned them, but none of the orange insulators showed any signs of breakdown.  This is all I have had the energy/time to check so far.  Will run through the other stuff soon, but have to be out of town for a few days, so will be next week earliest.  The coil is a "blue Bosch", the dist'r an 09 w/ induction points, so far as I know.  Standard JPS stuff. 

Another input: pls recall that after the carb rebuild, the car ran very well and smoothly.  That was Wed evening this week.  I drove it to Merklin's Sat.  ran well up to Chambersburg -- ~90 mi.  I topped up my gas (1/2 a tank, perhaps a bit more) in prep for the day of cruising in Ch-bg at a no-name station near Alan's house.  Troubles began to be noticed after that while we were out running.

How does it run when cold?  Sunday AM I fired it up, and it was the worst it has ever been.  Now it will not idle, and to drive it takes some doing, and the pops out the back now get up to the level of  gunshots.  Lots of raw gas is getting into the muffler, and being set off by the cylinders that are firing.  It will run, and if floored, will move out, but revs need to be up -- lots of pedal pumping.

I have seen Danny's ignition set up, and it is pretty cool, no doubt.  I could do that, but I'd wish to take on that upgrade only after I had figured out WTF is going on now first.

fuel filter (new) is in the back, per JPS build -- I have moved it to the aft corner.

I have a multi meter but need some hard data to check for.  So far the only thing I have above specifically to check is the running voltage at the coil.  Folks say check this or check that, but no suggestion for how to do the checking, what to look for, what is "good" and what is "bad" -??-  for example, the ballast resistor:  what is the resistance supposed to be?   The deal seems to be replace components until it runs properly.  Hmmmm -- well OK, 'spose I could do that, but would be great if we could ID a fault through specific diagnosis.  Asking too much?

Next effort will be to read the plugs, and do a compression check.

I seem to remember someone finding the induction points module securing screw came loose and it was wiggling around in there. Egads, another thing to check!

~WB

... not if you own a bunch of obsolete, NLA, 1960s Sun diagnostic equipment. You got an old oscilloscope laying around in your garage?

I've got a multi-meter, a timing light, and a bunch of spare ignition parts. It's what is required in the abesence of Mercury rocket era tools.

Honestly, if you don't ant to borrow a friend's stuff-- you can get an EMPI "screamer" kit with a coil, a distributor, and wires for a hundred bucks. They're Chinese junk-- but it'll show you what's wrong if you just start changing stuff.

I know it hurts the scientist in you, but sometimes the easiest way is the best way. Really.

Frazer, I'm a new VS owner and just getting my feet wet with the whole sorting drill, so I'll let the experts advise you.

But some electrical parts - like coils and plug wires - will look OK and even test OK when cool, but fail when they heat up.

Coils are notorious for failing that way, and the insulation in old plug wires can break down (electrically) and allow high voltage to short while still looking normal. The wires in my car lie right on top of the engine case for a good bit of their run, so they get very hot and have lots of opportunity to short out to the grounded case.

Like Stan said, with a stubborn problem like yours, sometimes it's best to just replace the cheap stuff to eliminate it as a cause.

And the coil and wires are some of the few things you can replace in these cars without a chiropractor.

Ah, but Kelly said "How does it run when cold?  Sunday AM I fired it up, and it was the worst it has ever been."  Something could have failed in the ignition system, but not yet so bad that it won't start, OR he is suffering from ethanol damage in the fuel system and may need to replace the pump and filters, flush out the lines, and seriously clean the carbs.  Since heat now seems not to be a factor, I am less confident that the ignition system is the culprit.

I'm sticking with my analysis, but I'me not there.

Look, I'm not an expert-- but I do troubleshoot mechanical equipment for a living, and I've made a good living at it. A toubleshooting flow chart is nice, but available less than half the time. Intuition and following some basic principles carries the day in many difficult situations. There's nothing as difficult as correctly guessing a problem when you are not standing in front of it, but some principles of troubleshooting apply.

1. In troubleshooting, as in life-- doing the same thing over and over and expecting a different result is the definition of insanity. ACVWs can make a guy crazy because there's so many primary systems that have parts of dubious quality. But the very fact that a guy as thorough as Kelly re-did the carbs (as thoroughly as it sounds like they were) points to the problem being somewhere else.
2. The fact that the ignition system hasn't even received a cursory look points to the problem being there.
3. The intermittent nature of the problem strongly points to ignition. Carburetor problems are almost always constant. 
4. Sometimes, the best thing you can do in a frustrating situation is to step away, and let somebody else look at it. When a guy gets emotionally invested in his diagnosis, tunnel-vision sets in. That's a bad way to see whatever is being missed.

Another cogent point regarding fuel quality:

"Bad gas" get blamed for a world of ills, and yet every car in America is running on it. I bought into the whole thing for a while, but the only guy I've ever known with an issue was Cory and his fuel-cell. Kelly's not running foam blocks in his fuel tank, so if he's got fresh lines, and his carbs were freshly cleaned, and he's got a good filter-- he's probably good for at least 5 years. I've never had a problem related to "bad gas", and I've purchased 91 and 93 octane all over the place. It's hard to get the last 5% out of an engine with this gas, but it isn't hard at all to keep it running well enough to go down the road without back-firing and farting out the carbs and exhaust.

That's all I've got to offer. Your mileage may vary. Forewarned is forearmed.

I had a malady a couple of weeks ago. The car just didn't "sound" right. The power just didn't seem there either. So whilst checking the carb sync, I caught the left carb not opening with the right, but the linkage was moving. Turns out the nut securing the linkage opening "cam" to the carb shaft had loosened and was slipping. I tightened it, did a re-sync and voila, back to perfect!

As a fellow JPS owner, I initially had the same popping, backfiring problems with my carbs.  Like you I added jet doctors and set the floats at 10.5 mm.   Put everything back together and like you, it ran fine for a while then the intermittent popping and running poorly started again.  I took the carbs back off, cleaned, and checked the floats and found the float drop was way off.  I reset them, put everything back together and it has run better than ever, ever since. 

With gas in your exhaust could it be that one of your carb float needle valve is not seating properly, allowing more fuel into the cylinders and not being burned, ending up in your exhaust?

Rob

2.5 turns out with bigger idle jets? WRONG! Anything more than 2 turns out on Webers is either the wrong jet or filthy rich, pick one. You can't arbitrarily turn the screws and say anything at all, it doesn't work that way. You need to adjust each cylinder for peak rpm , at idle, with engine FULLY warmed, period. Kelly, I'll have to give you a visit or something. I have a feeling you just need a little objective help. You're too close to the problem and missing something simple.

I wouldn't throw the Webers out just yet. Dells run , Webers run, but Dells don't automatically run any better.....I love Webers, they are as good as TITS! 

At the Palooza I offered to take a look, wondering why you didn't take me up on it?

Danny,

I would have loved to have you look things over, but at the time it was running pretty well at that moment, plus, there was little time. The run (Pumpkin, Palooza, whatever) is about having a good drive and schmoozing, and not getting all geeky over engine stuff -- unless of course there is a true breakdown, and then you have a hard time seeing what's wrong 'cause there are so many heads and hands in the back end.  In the carb rebuild, I did not swap out the float needles, as they looked and acted just fine.  I set the levels, which it needed a little bit, and called it good enough.  Perhaps something went wrong there.  -?-  Could pop the tops, and have a look.  Yanking the whole works down again, w/ carb bodies on the bench  is possible -- hey, I'm nearly expert w/ that R&R at this point -- but not something I'd enjoy.

And the jet Drs instruction says the mixture valves will need to be readjusted vs. what they were w/out the tube extenders -- but does not say whether should be in or out. OFF HAND, I'D GUESS OUT A LITTLE, BUT THAT IS JUST A GUESS. [Not Gerding on ya, just hit the caps lock key . . .]  In my defence, I would have loved to have you look things over, but at the time it was running pretty well at that moment, plus, there was little time. The run (Pumpkin, Palooza, whatever) is about having a good drive and schmoozing, and not getting all geeky over engine stuff -- unless of course there is a true breakdown, and then you have a hard time seeing what's wrong 'cause there are so many heads and hands in the back end.  In the carb rebuild, I did not swap out the float needles, as they looked and acted just fine.  I set the levels, which it needed a little bit, and called it good enough.  Perhaps something went wrong there.  -?-  Could pop the tops, and have a look.  Yanking the whole works down again, w/ carb bodies on the bench  is possible -- hey, I'm nearly expert w/ that R&R at this point -- but not something I'd enjoy.

And the jet Drs instruction says the mixture valves will need to be readjusted vs. what they were w/out the tube extenders -- but does not say whether should be in or out. OFF HAND, I'D GUESS OUT A LITTLE, BUT THAT IS JUST A GUESS. [Not Gerding on ya, just hit the caps lock key . . .] In my defence, the car started, idled and ran so well right after the rebuild that I figured I just got lucky w/ my mixture settings (2.5)  to get going. The snail said balance was very good.  My plan was to run it some and then tweak.  I was going to get you to give your magic touch at Alan's, but let that go in favor of having a good visit w/ the folks.

I have quite a list of "simple" checks to do here vis-a-vis the ignition, and I'll do it.  Next week.

I really Appreciate all the advice -- it is what I came for, and is taken under serious advisement.  Good stuff.

Txs

Gotcha Kel, but I would have preferred less fun and having you run home IN tune and smooth. It's really no problem. Got to visit the Drake clan and Chuck and Todd soon anyway, we should make it a point this fall if we can.

Do you have a copy of the Weber instructions I worked up for everyone? If not, I can send it to you. Unfortunately, Harney's Carb Clinic is no longer on the web. But aircooled.net's stuff is pretty good. Let me know what you need.

Danny,

Most of the Harney Tech articles are here, in the Knowledge section.

Still waiting on Theron to upload the tech article on tear down and cleaning. That one has photos.

Hi Danny I am interested in the Weber instructions you metioned.

What do you need for a copy?

I have the Tomlinson (?) Weber book, plus have seen lots on the net, and watched several folks (you included) do the deed.  i think I get the deal w/ setting the mixture.  HOWEVER, the thing is running so crappy right now, not sure this little subtlety would even be possible.  It really will not idle, so tweaking the mixture is ????

My current mantra is like the best advice you can get in what to look for in real estate: ignition, ignition, ignition.  Will chase that little fox for a while.  Without really knowing what should be first, I will (1) pull and inspect the plugs (2) run a compression check (3) measure voltage at the coil low side (4) check timing.  Could add (5) adjust valves, but they were done recently and have never needed very much.  Anybody want to add to this list??

Pull the cap off and be sure the ignition module is secure.

That's probably the most succinct thing I have yet seen on this thread........

Forget adjusting the Valves.  

Start with spraying carb cleaner around the manifold intersections to see if you have a leak, then, if that proves OK go after the ignition (but check the ignition module to make sure it's OK, anyway).  I agree that, given the relatively low cost of ignition parts, you could shot-gun it by doing some mass-swapping out and just getting over with it.  I agree with Danny- there's really nothing wrong with Webers.  They have etheir own idiocyncrices which need to be addressed, but they're OK carburetors.  I would prefer to run Dellortos, but then I've already made it known that I'm lazy, right?